Much research on complex biological systems at all levels of structure shares the need for rapid calculation of three dimensional structures and their visualization and manipulation in real time. Structural data at the molecular and cellular levels of the core user group are derived primarily from electron microscopy, while images of living cells are obtained by fluorescent light microscopy; data at the organ and tissue level are derived from living people by the techniques of computed tomography (CT) and magnetic resonance imaging (MRI). The VAXserver 3900, X-windows terminals as well as the Stardent supergraphics computer with enhancements are needed by all users of the facility for computation and visualization of data. The Optronics interface is needed for digitizing data on the existing Optronics microdensitometer. The fluorescent light microscope workstation and CCD and SIT cameras and are necessary for collecting data from living cells. The core user group consists of 14 scientists from six different departments or institutes pursuing ten research projects. The subjects studied by the major users are diverse: muscle thick filament structure, including the backbone and crossbridge interactions, dynamics of development and other changes in muscle and non-muscle cells, excitation-contraction coupling, structure and function of retinal circuitry, role of oncogenes in growth and differentiation, alveolar fluid uptake, fibrinogen and fibrin structure and assembly, and imaging of anatomical structures by CT and MRI. Most of the core users have some experience with computer image processing and graphics applied to biological problems and have research programs that have been limited by the currently available instrumentation. The requested equipment will open exciting new research possibilities for a wide variety of scientists at the University of Pennsylvania.